title: Methylcobalamin facilitates collateral sprouting of donor axons and innervation of recipient muscle in end-to-side neurorrhaphy in rats.
abstract: Using ulnar nerve as donor and musculocutaneous nerve as recipient we found earlier that end-to-side neurorrhaphy resulted in weak functional reinnervation after lengthy survival. End-to-side neurorrhaphy however is the sole choice of nerve repair at times and has the advantage of conserving donor nerve function. Here, we investigated whether myelination-enhancing agent methylcobalamin and motoneuron trophic factor pleiotrophin enhances the recovery after end-to-side neurorrhaphy. Methylcobalamin significantly increased the expression of growth associated protein 43 and S100 protein and βIII tubulin in musculocutaneous nerve 1 month after neurorrhaphy suggesting the ingrowth of ulnar axonal sprouts in reactive Schwann cell environment. Upper limb functional test, compound muscle action potential measurements, motor end plate counts, and axon and myelin analyses showed that methylcobalamin treatment alone or with pleiotrophin improved the recovery significantly, 3 and 6 months post-surgery. There were fewer axons, closer in number to that of the intact recipient nerve, found in the distal repaired nerve of the methylcobalamin-treated than that of the vehicle control, suggesting that methylcobalamin facilitates axonal maturation and eliminates supernumerary sprouts. In conclusion, our results showed that methylcobalamin does indeed enhance the recovery of peripheral nerve repaired in end-to-side configuration.
authors.affiliation: Department of Anatomy, Faculty of Medicine, Chung Shan Medical University and Department of Pediatrics, Chung Shan Medical University Hospital, Taichung City, Taiwan.
authors.forename: Wen-Chieh
authors.initials: WC
authors.lastname: Liao
authors.forename: Yueh-Jan
authors.initials: YJ
authors.lastname: Wang
authors.forename: Min-Chuan
authors.initials: MC
authors.lastname: Huang
authors.forename: Guo-Fang
authors.initials: GF
authors.lastname: Tseng
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001369:Axons / Q000187:drug effects / Q000502:physiology*; D015153:Blotting, Western; D002352:Carrier Proteins / Q000494:pharmacology*; D016207:Cytokines / Q000494:pharmacology*; D019922:GAP-43 Protein / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects*; D008297:Male; D018482:Muscle, Skeletal / Q000187:drug effects / Q000294:innervation*; D009138:Musculocutaneous Nerve / Q000378:metabolism / Q000601:surgery; D059348:Peripheral Nerve Injuries / Q000601:surgery*; D051381:Rats; D017208:Rats, Wistar; D009418:S100 Proteins / Q000378:metabolism; D014404:Tubulin / Q000378:metabolism; D014459:Ulnar Nerve / Q000378:metabolism / Q000601:surgery; D014805:Vitamin B 12 / Q000031:analogs & derivatives* / Q000494:pharmacology
chemical_list: D002352:Carrier Proteins; D016207:Cytokines; D019922:GAP-43 Protein; D009418:S100 Proteins; D014404:Tubulin; C066845:pleiotrophin; C019476:mecobalamin; D014805:Vitamin B 12